A sensor network can include spatially distributed, autonomous sensors useful for monitoring an area. For example, the sensors may be used to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants. Sensor networks are used in many industrial, military, and civilian applications. For example, sensor networks can be useful in monitoring or controlling industrial processes, machine health, environment, habitat, healthcare, home automation, traffic control, and so forth.
Sensors in sensor networks can be nodes in the network. In the case of wireless sensor networks, each node may be equipped with a radio transceiver or other wireless communication device, a small microcontroller, and an energy source (such as a battery, for example). Sensors can be created with a variety of sizes, costs, or functionality, and the sensor variations can be a function of the complexity of the purpose for which the sensor network is being implemented. For example, different sensor network uses may involve different resource usages in terms of energy, memory, computational speed, and bandwidth.
Previous systems for placing sensors or identifying a precise location of sensors in a sensor network have a number of drawbacks. Prior art systems can be time-consuming and expensive to implement, or may be harmful to the environment. For example, some systems use heavy machinery to perform surveys, set up a cable grid over the landscape, plant flags identifying locations to place sensor devices, etc. Use of heavy machinery can be damaging to the environment. Furthermore, where the sensor network is established over rugged terrain, the area for the sensor network may be inaccessible by machine. Systems involving hand-planting of flags as part of a survey to identify sensor device locations, or simply having workers approximate the appropriate sensor location can result in sensors not being precisely located. For some sensor applications, greater precision is desired than may be achieved using such a system. Other systems have used Global Positioning System (GPS) devices to precisely determine locations for sensor devices. However, GPS systems can also be expensive and result in large time expenditures while waiting for an update of the precise location of the worker and then determining where that location is with respect to where the sensor is to be placed.